Presently, latitude and longitude are utilized to indicate a coordinate of an entity on the Earth; the latitude is measured from the equator with positive values going toward north and negative values going toward south. The longitude is measured from the Prime Meridian (which is the longitude that runs through Greenwich, England), with positive values going to east and negative values going to west. Therefore, for instance, 65 degrees west of longitude, 45 degrees north of latitude represents −65 degrees longitude, +45 degrees latitude.
On the other hand, the prior methods for representing a geographical coordinate of an entity on the Earth is not too convenient to be recorded, and is very difficult to be exploited in many existing navigation equipments and systems.